Insulin dependent diabetics are required to adhere to a strict prescribed regimen of liquid insulin injections in order to manage their diabetes. One popular means of administering insulin is by means of a reusable transdermal liquid dosing device commonly referred to as an “insulin pen”, which includes a plastic syringe with an insulin reservoir and a cap that covers a proximal end of the syringe from which the insulin is delivered by means of a hypodermic needle.
It is known from several published studies that because diabetics are required to take multiple daily injections of insulin, the injecting procedure very quickly becomes so routine that an individual dose can easily be forgotten. There is generally no simple and reliable way to tell—using commonly prescribed insulin pens or by examining the injection area—whether or not a given dose has been administered. Missing a prescribed insulin dose or inadvertently taking too many doses within a short period of time can lead to serious short and long-term health risks and complications for a diabetic person, including hyperglycaemia and hypoglycaemia.
Several attempts have been made in the past to solve this problem. For example, US-2009/0076458 to Nielsen describes an injection device that is itself capable of emitting a flashing light signal indicating the time elapsed since the last injection. The flashing light is provided on the body of the device. While US-2009/0076458 seeks to solve the same problem as the present invention, it has the disadvantage of forcing a diabetic person to abandon and discard their preferred or prescribed insulin delivery system in favour of a new system, which may be economically prohibitive for many users. Another disadvantage of the injection device disclosed in US-2009/0076458 is that the user would have to learn the meaning of the particular flashing light sequence used to indicate the time since the last injection. This could be a significant obstacle for some diabetics, in particular the young or elderly.
US-2004/0062148 to Skyggebjerg discloses a timer device that includes two device portions that detach from each other and together form a single portable unit. An insulin pen in provided in one of the device portions and the two device portions are held together when the pen is not in use. Separation of the device portions causes a control action to be actuated. This solution suffers from the disadvantage that the preferred embodiment is complex and requires a measure of user sophistication and discipline in using the device, as well as requiring a separate dedicated and larger device to be carried. In other described embodiments, one of the device portions is integral with a cap adapted to cover a distal portion of the first device. The disclosure is silent on any practical or cost-effective means of detecting separation of the device portions in that described embodiment or ensuring proper cooperation between the cap and distal portion of the first device.
Systems have been proposed in which medication devices are placed in register with docking-stations that function as control and indicating devices, for example WO-03/063754 and WO-99/43283, the latter of which discloses a sleeve-like indicating device that can be attached to the rear end of an injection pen. These devices suffer from the disadvantage that an additional piece of equipment must be used in conjunction with the insulin pen, and are generally complex and expensive.
US 2002/0096543 discloses a portable control device for monitoring doses of insulin administration. In certain disclosed embodiments, a control device is provided as a separate piece that can be fixed to a conventional cap of an injection pen, and the body of the pen includes a resonance circuit to enable removal of the cap to be detected. The control device includes a transmitter that communicates with a remote console to remind the patient to take the dosages, and uses a system of coloured lights to indicate that a dose should be taken. The disclosed embodiments are complex to use and understand, may require discarding or adapting existing prescribed preferred or prescribed insulin delivery systems, as well as being prohibitively expensive for many users.
The applicant believes that the abovementioned drawbacks at least partially account for the fact that the majority of insulin pens currently used are not used in conjunction with any means that would help a user determine whether a given dose has been administered.